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Posted By Discussion Topic: Triple 97's -- page: 1 2     kelroy 04-11-2011 @ 7:29 AM reply profile send p.m. Member Posts: 12 Joined: Oct 2009 Stroker you're right it does sound great! But I haven't got it exactly right yet - the MSD dist. comes with several available advance curves, I've resigned myself to trying each, hoping to hit the right combo. But that's OK, tinkering is part of the fun! Stroker 04-01-2011 @ 3:45 PM reply profile send p.m. Senior Posts: 1460 Joined: Oct 2009 Kelroy: Generally speaking, with a cam such as the Isky 400 Jr which carries about 258 degrees duration, you can bump the timing up a little earlier in the curve, relative to a stock 8BA cam as at low rpms, your effective (actual, not calculated) compression will be less due to the increased overlap, (the 400 uses the same Lobe Separation Angle as the stock cam) hence the tenancy for low rpm "pinging" under load will be decreased. The 400 Jr. "comes-on" at a fairly high rpm, so don't expect a lot of low end torque. You have a very nice combination, with the 3-97's, displacement, cam combination etc. Problem will be that it works best in a very light vehicle. This will not be a motor you'd want to use for towing, but I'm sure that besides looking good it will sound righteous ford38v8 04-01-2011 @ 3:20 PM reply profile send p.m. Senior Posts: 2769 Joined: Oct 2009 Kelroy, when you were a Teen, you wouldn't take advice. Now that you are old and wise, you've found that as advice is cheap & free, anyone not taking all he can get at those bargain prices is usually a wet-behind-the-ears teenager. Alan supereal 04-01-2011 @ 12:51 PM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 The advance curve info should be furnished with the cam. I can't find that cam in my references, but if you don't have the numbers, I'm sure they can furnish it. As mentioned earlier, the stock advance at 2200 RPM is about 12 degress. Obviously the Isky cam will be considerably different. kelroy 04-01-2011 @ 10:25 AM reply profile send p.m. Member Posts: 12 Joined: Oct 2009 Thanks again Guys, You know when I was a teenager I never needed advice, now it seems I can't take a single step without advice or directions! Supereal, Sorry I didn't mention the cam, it's an Isky 400 junior. Coincidently, I was just trying to determine the best advance curve. This distributor has 4 advance Stop positions, 18, 21, 25, and 28, what do you guys think? JM 03-31-2011 @ 12:14 PM reply profile send p.m. Senior Posts: 823 Joined: Oct 2009 You might want to contact Uncle Max or Charlie, NY over on the Ford Barn Forum. They are both excellent at setting up multi carbs on Flathead's. I constantly confer with Uncle Max on how to build and set up 97's. He is also a great source for 97 parts, rebuilt 97's or the new 97's from England. JM supereal 03-31-2011 @ 10:34 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 IO think Dan (Stroker) covered it all. The problem with all carbureted engines is producing a smooth transition from idle to the best part of the power band. The factors in performance involve compression, spark advance, and mechanical efficiency. At the point the torque and brake horsepower curves cross is the "sweet spot" of performance. For the Ford flathead, it is about 2,200 RPM at full throttle. Thus the intake capacity has to be tailored to that scenario for best overall operation. Multiple carbs were mostly used for either circle or drag racing, where low speed was not important. For street, they do look good, of course. I'm not familiar with all the MSD ignitions, but I assume they did, or should have, provided the info you need regarding advance curves. My charts show that advance of about 12 degrees at 2000 RPM is required, rising from the standard 3-4 degrees at an idle of 500. With unaltered 97 carbs, progressive linkage is probably the only way to achieve a decent idle. You didn't mention the cam, so I assume it is stock. kelroy 03-31-2011 @ 6:03 AM reply profile send p.m. Member Posts: 12 Joined: Oct 2009 Stroker, Great article! It is now all beginning to make sense! My car came with an MSD distributor built to advance via either mech. or vacuum, (the one not used is to be blocked off) I've got to get into it, I suspect it was just dropped in as it came in the box; and the vacuum line hooked to the manifold. I appreciate everyones help, maybe I'm on the right track! Stroker 03-30-2011 @ 2:55 PM reply profile send p.m. Senior Posts: 1460 Joined: Oct 2009 Your biggest headache will be the distributor. The stock Ford/Merc. side mount distributor cannot be used with anything except a stock 49-53 carb with a venturi vacuum source port. Manifold vacuum won't do it. The reason is that the distributor has no mechanical advance system, but rather uses the vacuum can to time the spark based on the velocity of air in the carb venturi. About the only way to put either multiple carbs or a 4 bbl carb on these engines is to go to an aftermarket distributor such as the venerable Mallory (still available) which have a mechanical advance system or switch everything back to the 48 and earlier system with the front mount distributor. Attached is some excellent advice from the Late Barney Navarro that was written when your car was new. 37RAGTOPMAN 03-30-2011 @ 2:52 PM reply profile send p.m. Senior Posts: 1965 Joined: Oct 2009 If you back off the throttle plates screws on the 1 and 3 carb,ALSO disconnect the linkage, make sure the plates are closed, now you should be able to make it idle,with center carb, depending in what condition the engine is in,compression ,timing etc, I thought the 1 and 3 carbs should come in at about half throttle off the center carb,and all 3 should be open at full throttle. years ago a friend on mine had a 50 with twin carbs, and the only way we could get it to have pickup was to put a weaker spring on the vacuumn advance. hope this helps, have fun,,,37 RAGTOPMAN

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